Abstract
Background: Intratumor microbiota are increasingly implicated in cancer pathogenesis, with emerging evidence suggesting their role in regulating DNA methylation pathways in hepatocellular carcinoma (HCC). This study investigates the interactions between specific bacterial genera and key DNA methylation-related genes in HCC tissues. Methods: Tumor and adjacent normal tissues from 72 HCC surgical patients were analyzed. Bacterial composition was characterized via 16SrRNA sequencing, while quantitative analysis assessed the abundance of differential bacterial genera and expression of DNA methylation pathway genes linked to HCC outcomes. Results: Six bacterial genera exhibited differential abundance between tumor and normal tissues: Propionibacterium, Mycoplasma, Variovorax, OPB41, unclassified_Bifidobacteriaceae, and Rikenellaceae. Key gene-microbiota correlations included: Negative associations of Propionibacterium with SPOCD1 and EOMES; Negative associations of Mycoplasma with BMI1 and EZH2; Negative correlations of Pseudomonas with BMI1, EOMES, EZH2, and SPOCD1. Additionally, Pseudomonas abundance was negatively correlated with both Propionibacterium and Mycoplasma. Conclusion: The identified microbiota-gene interactions reveal potential mechanistic links between intratumor flora and HCC progression via DNA methylation regulation. These findings highlight novel targets for further exploration of HCC therapeutic strategies.